Superabsorbent polymers (SAPs) are synthetic polymer materials having a capacity for absorbing 500 to 1000 times their own weight in moisture. Although developed for practical use in sanitary items such as disposable diapers for children, sanitary pads, etc., SAPs now find additional applications in a variety of fields including raw materials in soil conditioners for horticulture, water stopping agents for civil engineering and construction applications, sheets for raising seedlings, freshness preservatives for food distribution, goods for fomentation, and the like.
Absorption under pressure (AUP) or permeability, which is one of the major properties of SAPs for use in diapers, may degrade as the SAPs are broken down during manufacture into diapers. In consideration of the degradation thereof, the physical properties of SAPs should reach sufficiently high levels. However, various physical properties of SAPs are in a trade-off relation. Due to this limitation, there is therefore a need for the development of a superabsorbent polymer provided with various satisfactory physical properties that exist in harmony with each other.